1. Field of the Invention
The present invention generally relates to a roller bearing and, more particularly, to a roller bearing such as, for example, a roller bearing having an inner race and needle roller bearing having a roller retainer, of a kind used in the field of application similar to that of the full complement roller bearing, for example, in a seat reclining mechanism, motorcycle rear suspension link, roller rocker arm and planetary reduction gear unit.
2. Description of the Prior Art
The full complement roller bearing is generally used in the field of application in which the roller bearing is required to have a large load bearing capacity for a limited outer diameter of the roller bearing. Since the full complement roller bearing makes no use of any roller retainer having retainer pillar intervening between the neighboring rollers, both of the number of the rollers used and the load bearing capacity can be increased as compared with those of the retainer type roller bearing.
As is well recognized by those skilled in the art, the full complement roller bearing makes no use of any retainer and, therefore, some or all of the rollers tend to drop off before mounting of the roller bearing onto a machine component and, at the same time, the number of assembling steps tend to increase. Also, as shown in FIG. 11 showing a fragmentary longitudinal sectional representation of the full complement roller bearing, even where the rollers 30 used in such full complement roller bearing are assembled using outer and inner sleeves 31 and 32, the outer and inner sleeves 31 and 32 are required to be removed during the assemblage. Accordingly, with the full complement roller bearing of the type shown in FIG. 11, not only is the number of assembling steps increased, but also increase of the cost and the environment-related problem tend to occur because of the use of the sleeves 31 and 32.
In view of the foregoing, various suggestions have hitherto been made to avoid the drop-off of the rollers. One of those suggestions includes the use of the rollers each having its opposite ends formed with coaxially extending steeples so that the press-worked outer race, i.e., the outer race formed by means of a press work, having collars formed at its opposite ends can saddle each roller with the collars receiving the steeples of the respective roller. See, for example, the Japanese Laid-open Patent Publication No. 6-307456.
Another one of those suggestions includes filling a thermally curable grease to render the rollers of the full complement roller bearing to be non-detachable such as disclosed in, for example, the Japanese Laid-open patent Publication No. 7-238940.
The full complement roller bearing of the structure, in which the steeples are employed at the opposite end faces of each roller to achieve the non-detachability of the rollers, i.e., to render the rollers to be non-detachable, has the following problems:                The effective length of each roller tends to be reduced a quantity corresponding to the sum of axial lengths of the opposite steeples formed therein.        Since the opposite ends of each roller are axially outwardly steepled, the frictional wear of the roller end faces tends to be prominent when the full complement roller bearing of the specific structure is employed in the environment where an induced thrust force is large.        Since the opposite ends of each roller must be processed in any way to have the steeples, the respective roller is costly as compared with the roller having opposite flat end faces.        
On the other hand, the full complement roller bearing of the structure, in which the thermally curable grease is filled to constrain the rollers in a non-detachable fashion, has the following problems:                The use of the thermally curable grease limits the temperature under which the full type roller bearing of the specific structure can be used and operated.        Means for lubricating the bearing that can be employed, for example, the type of the grease used and the type of oil used, are limited.        
In view of the foregoing, it has been suggested in, for example, the Japanese Patent Application No. 2003-285566 that in the retainer type roller bearing a generally ring-shaped roller retainer having a plurality of pockets spacedly defined therein in a direction circumferentially thereof is made of a synthetic resin capable of deforming in a direction radially thereof and, on the other hand, the retainer pillar present between the neighboring pockets retains the respective roller from an inner diametric direction and has an outer diameter smaller than the diameter of the pitch circle in which the rollers are arranged.
According to the suggested design, the rollers can be placed inside the respective pockets of the roller retainer when after the rollers have been mounted around an inner periphery of the outer race, the roller retainer is inserted radially inwardly of the circular row of the rollers while a portion of the roller retainer is radially deformed against its own elasticity by the application of an external force and subsequently releasing the external force to allow the roller retainer to restore to the original position with the rollers consequently positioned inside the respective pockets.
However, the structure of the retainer type roller bearing discussed above is applicable only to a specific roller bearing, i.e., the roller bearing having an outer race and cannot be applied to such a retainer type roller bearing having an inner race 33 and a roller retainer 34 as shown in FIG. 12. In addition, when the roller bearing of a type having a raceway (either an outer race or an inner race) is compared with the raceway-less full complement roller bearing, i.e., the full complement roller bearing having no raceway, of the same sectional height, a problem has been found in that the roller bearing of the type having the raceway tends to have a reduced load bearing capacity.